Dependable Infrastructure Services for Mobile Devices.
At the brink of the 21st century, ubiquitous computing
systems and prototypes suffered from numerous drawbacks with respect to dependability in the broadest sense.

This was for several reasons:
First, ubiquitous computing systems were vulnerable to service disruption
and temporary failures because they often relied on a fixed set of technologies for communication,
sensing, and actuation.
Secondly, as a rule, they did not or only in a very limited fashion exploit the full
spectrum of resources that were readily available and implicitly provided by existing ubiquitous computing environments.
Thirdly, they lacked support for the ever growing number of small, resource-limited
mobile devices that were appearing with the continuing realization of Marc Weiser's ubiquitous computing vision.
As size and cost restraints imposed stringent resource restrictions on mobile ubicomp devices,
as a result, these devices were in general more vulnerable to hardware and software failures than traditional
desktop-sized computer equipment.

One of my dependability research activities in ubiquitous computing was the investigation of how dense
distributions of smart entities can contribute to the realization of
dependable services and applications.
More specifically, I developed and prototypically implemented a middleware architecture
that uses dense RFID tag distributions (so-called super-distributed
RFID tag infrastructures) over surface areas
to provide robust and reliable RFID-based services to mobile devices
by exploiting tag redundancy.

Furthermore, I looked into means to reduce the users' dependence on individual
mobile user devices while retaining the benefits and conveniences of handhelds
featuring customized and personalized functionality. In this context, we proposed
the concept of instant personalization,
and provided a prototypical implementation on internetworked personal digital assistants.

Another aspect of my research was the exploitation of heterogeneous redundancy
that typically is available in ubiquitous computing environments, with the goal of
improving the robustness and dependability of fundamental ubiquitous
computing services. One example for this is a
robust probabilistic
positioning service architecture we developed, which employs an available ubiquitous computing infrastructure
for the self-localization of small, mobile devices. The idea was to tackle the aforementioned dependability issues
by improving the availability and quality of the positioning
process by merging the location information obtained from an arbitrary number of sensors, using
sensor fusion and map knowledge.

Social Implications and Challenges of Ubiquitous Computing.
In the year 2000, the field of ubiquitous computing was still emerging and
steadily making progress and gaining attention in both academia and industry.

While new gadgets and
smart home appliances could not appear fast enough for many technologists,
such rapid introductions of new technologies often came with unexpected
side-effects. Due to the unique scope of ubiquitous computing as a tool for
our everyday life, these side-effects can have serious implications for the
way we live in the future. We found it important to explore potential effects
that a large-scale deployment of ubiquitous computing technology in the
real world may have. Thereby, our intention was to raise awareness for a technical
design that takes the concerns of the average citizen into account, as well as to
serve as point of departure for further interdisciplinary research in the field.

EntryPoints into the ETH World Infostructure.
The EntryPoints project was part of the virtual campus project ETH World
(formerly available under www.ethworld.ch, project home page now offline)
and addressed the coupling of the physical campus infrastructure
with the ETH "infostructure".

By embedding hyperlinks into the ETH campus
and attaching information to physical objects, visible entry points into
the information space of ETH World were created, enabling a natural interaction
between the physical and virtual environment and thus providing ubiquitous
access to ETH World. Providing location information for physical rooms and
artifacts simplified the retrieval of information that is associated with them
and also allowed people to navigate more easily. Through ongoing evaluation,
important questions regarding privacy and social acceptance of such a paradigm
were analyzed.

ETHOC - Every Thing Has Online Content.
In a ubiquitous world, physical objects (like paper documents)
possess an electronic representation, so-called virtual counterparts,
which supply additional functionality and resources.
The ETHOC system virtually linked
printed documents with virtual counterparts. The user could access and interact with
the virtual counterparts by means of various mobile devices.
Bar codes and mobile bar code readers were used as the linking technology
to access virtual resources as well as additional virtual features
of the enhanced printed documents.

UPDATE: Please note that the official ETHOC Home Page (formerly available at www.ethoc.ethz.ch) with the ETHOC Web
interface is no longer online at ETH Zurich.

Moving from platform to platform to perform their tasks,
mobile agents are subject to attacks by potentially malicious hosts.
As a consequence, it is desirable to protect these agents against manipulations
and fraud while also maintaining a maximum degree of inter-operability and flexibility.
In this context, we investigated and developed generic and secure services
for autonomous agents as part of open mobile agent systems (IBM Aglets) and applications,
employing the IBM JavaCard as a trusted hardware platform.

In the year 2000, I was involved in the initial planning and direction of the
ETH Zurich Wireless LAN Project,
where we installed the first large-scale Wi-Fi network in our office building (IFW/RZ building) at
ETH Zurich. Today, Wireless LAN access is up and running in all parts of the
ETH university campus. In the early days, I also administered the initial project home page,
which offered information on WLAN services available at the ETH Zurich, including information on technical
aspects, security bulletins, required equipment, drivers and support.